If you're a founder you should anticipate these kinds of questions and have answers for them that make sense; if you ask these kinds of questions you should expect an actual answer, even if you don't agree with it.
Edit, to hopefully avoid some predictable replies:
- If the point is "don't be a jerk" then fine, there's a way to ask these basic questions without being discouraging.
- The author is right if the project isn't supposed to be a business. "Why would someone use your hobby language instead of C++" is a stupid question because the point of writing a hobby language is the fun of writing it.
But if someone is putting their life savings into a business idea and can't answer the most basic questions about it... Maybe they need a little discouragement.
Edit, again:
Also, I'm not a founder, but I have a side project, and I've gotten these sorts of questions about it... and I love them! Because it's a starting point into talking about my side project, which I love doing with people! I'm not discouraged by someone questioning why I'm building my thing, because I know perfectly well why I'm building my thing and I enjoy sharing that with people.